Back in 2010 we reviewed the MEElectronics M6 earphones, and liked them. The company's S6 earphones are very similar to the M6s, though the S6s are marketed as offering "enhanced sweat resistance." And the Sport-Fi S6 package includes a neoprene armband to stow your mobile device in during athletic activity.
In case you haven't heard of MEElectronics, it's known for producing good value earphones and we've given high marks to several of its models, including the comfortable A151, bargain-priced HT-21, and Bluetooth Air-Fi AF32 headphones.
Personally, I was less impressed with the Sport-Fi S6s. They actually sound decent if you can get a tight seal (as with all noise-isolating earphones), but I did have trouble getting a good seal with any of the included eartips -- and MEElectronics throws in six different sizes.
If you can get a tight seal, there's ample bass, and while they don't produce terribly detailed sound, they deliver reasonable clarity for affordable in-ear headphones.
One of things I didn't like about them is that they're bulkier than your typical earbuds. You're also meant to wrap the cord around the top of your ear and around back of it; the cord is stiffer at the top and has memory wire that you form into a sort of hook around your ear. It can require a little extra time to get everything to fit properly, which may bother some people.